Treatment of cellulosic fibers



April 17, 1951 H ROMEYN, JR 2,549,014

TREATMENT OF CELLULOSIC FIBERS Filed June 22, 1945 Patented Apr. 17, 1951 UNITED STATES PATENT O F FI CE TREATMENT OF CELLULO'SIC FIBERS Hendrik Romeyn, Jr., Nutley, N. J.,;assignor yto United States Rubber Company, New York,

N. Y.,- a corporation of New Jersey Application June .22, 1945, SeIaINO. 600,902

2 claims. l

This inventionrelates to improved cotton yarns and cords, and to a method of improving Vtheir tensile strength.

The invention resides inthe discovery that cotton yarns and cords, and especially yarns and cords of grey cotton, maybe endowed with markedly greater tensile strength per unit weight (measured atordinary temperatures) when the yarn or cord is subjected to a combination of two treatments, namely: (a) treatment withan aqueous bath, preferably a slightlyalkaline aqueous solution-from the class consisting of dilute aqueous solutions of xed alkalis, aqueous solutions of ammonia, andaqueous solutions of readily water-soluble amines; `and (b) treatment with a hot non-aqueous bath consisting `essentially of an organic solvent, preferably selected from those solvents having boiling points -which will permit liquid treatment at 50-1'50 C. at atmospheric pressure, and at thesame time will Apermitsolvent-volatilization during subsequent drying. The best results-are obtained when tension is applied to the-yarn or cord during .part or-all of the treatment in each bath, and during the `subsequent drying It has beenffound that the effects resulting from the combination of the two treatments are much greater than the sum of the individual effects of the two treatments upon .separate yarnsorA cords.

Grey cotton refers to cotton bersyarn,cord, or thread containingsubstantially all the natural cotton waxes, and cotton waxes means that group of non-cellulosic water-insoluble components ofthe `grey cotton which are characterized by extremesolubility in hot ethyl alcohol.

rlihe aqueous bath (a) has the propertyof swelling the cellulose without materially altering the chemical composition of the cellulose bers Vconstituting the yarn or cord; the non-aqueous'organc solvent bath (b) is capable of swelling or dissolving the so-called cotton waxes. Either bath may be used rst in the successive treatments. The time of treatment in each bath should be for at least Ve minutes but not to an extent to substantially alter the final "softness and pliablity of the yarn or cord. The tension applied to the cord or yarn during the treatment should preferably not exceed 40% of the breaking stress of the untreated cord or yarn' if 'the continuous method is used; in batch treatment on spools, highertension may be required. The

2 dium carbonate, triso'dium :phosphate Concentrations of .from v0.1% to 2% are usefuLhigher concentrations giving no added benetand being `disa'dvantageous becauseV they may impair the tensile strength. iSuch ,tendering of the `cords is avoided by using instead a volatilebase which is completely removediin the subsequent drying .of

' the cord.

the :solvent treatment usually contains upwardsl of 40% of the ethanol-extractable material :ini-

' tially present.4

' .The-.organicsolvent'of A(l1) may fbe'any wellknown resin solvent or gum solvent, or mixture of such, preferably (but not necessarily) boiling in the range iro'mabout 100:C. .tol about 11.8020.. and being capable of dissolving cotton waxes.

' Very goodresults are-obtainedwithalleyl acetates treated yarn or cord is subsequently dried under l in which the alkyl -group 'comprises from 3 to "5* carbon atoms, for-example, -amyl acetate, or -with toluene, l-tricl'iloroethylene, pyridine, -or fbutanol. Gther solvents such as lxylene, solventnaphtha, petroleum ether,- amyl alcohol, cyclohexanone, di-

acetone alcohol, diethyl ketone, lbutyl ethyl #ketone, propyl acetatebutyl acetate, isobutyl ace-- tate, butyl lactate, ethylbutyrate, methyl-Cellosolve, diethyl carbonate, -vethylene'chlcrohydrin, amyl-fethy-l ether, diclilorodiethyl Y ether, V-isoamyl ether, morpholine, `piperidina rand dioxane Amay also bel used.

The two treatments v(at) and=l(b) may be Vcombined successively in: a continuous process,ffsho-wn diagrammatically in Figure 1 of the drawing, wherebyfthe n.yarn -or-fcor'd is` passed first through one ibathandgthen through the other, vandnis nally dried. Aiternatively,- the yarn or tcordl may be passed through or -undervr'a-spray of thessolutions, Ain succession.

- Alternatively; the two treatments: may"v heap# plied in-a batch processfshown diagrammatically by Figure 2 of 'the"drawingf` in which -yarn orf'cord yarn or cord is then subjected to tension (as by re-winding under tension), and is then treated by the second bath. Thereafter, the yarn or cord is again subjected to tension (as by re-Winding under tension), and is dried under tension. In this batch process higher tensions (up to 75% of the breaking stress of the untreated material) may be applied, since the tension at xed elongation rapidly decreases immediately after winding. By suitable adjustments of the factors of time and tension, products may be made by the batch process that are identical with those made by the continuous method described above.

The yarn or cord may be-so treated as to have either high tensile strength and low stretch, or a less increased tensile strength and a higher stretch. The yarns and cords may be used in the manufacture of sewing threads, tire cords, and many kindred products. The yarns and cords processed according to the invention may be employed as such, or combined with other processing, for the fabrication of various articles, e. g., hose, tires, belting, or other strain-resisting elements, and for the preparation of various fabrics, woven, knitted, or braided.

The invention may be applied to grey cotton in various forms, e. g., single yarn, plied yarns, cords, and cables.

The expression stranded cotton libres is to be understood as meaning cord, yarn, plied yarn, strand, thread, string, or the like.

' The treated yarns or cords may be subsequently rubberized, as in the manufacture of tire carcasses, but it will be apparent that the invention may be adapted to various uses not requiring rubberizing, and that the production of unrubberized fabrics including the treated cotton is also Within the broad scope of the invention.

' The following examples are given to illustrate the invention, without conning it thereto, the parts or concentrations being by weight. In Examples 1 to 15 the strength tests are made at 70- F. and 65% relative humidity (except as noted in Example 1,2). The calculation of percent increasein strength is made on the denier basis (except in Example 12).

Example 1.-Cntz`nuous process-Figure 1 18/4/3 cotton tire cord supplied from any conventional tube or spindle I is passed rst through a tensioning device consisting of a snubbing bar 2 and a dead load pulley 3. Weight attached to the pulley is suiiicient to maintain a tension of 0.9 lb. on the cord in transit, The cord is then passed through a bath 4 consisting of amy1 acetate heated to a temperature of 90 C. The cord traverses the amyl acetate bath at the rate of one foot per minute; each individual point on the cord is in contact with the amyl acetate for about 10 minutes.. The cord is next passed through a bath 5 consisting of an aqueous 0.28% solution of ammonia maintained at C., the length of path likewise being such that the cord is in Contact with the ammonia for about 10 minutes. The cord is next passed through a chamber 6 in which dry air at C. is circulated, the cord remaining in this chamber for about 21/2 minutes. The cord is finally wound on a spool at the positive drive wind-up mechanism I which provides the power necessary to pull the cord through the equipment. The cord so treated shows substantial improvements in strength and in fatigue life, with a corresponding reduction in stretch as illustrated by the following test data:

18/4/3 Gord Untreated Treated as 18/4/3 Described Cord in Example 1 Strength:

in lbs 17.6 23.6 in gms/denier 2.02 2. 94 Per cent increase in strength. 46 Stretch:

at l0 lbs., per cent 5.94 3. 45 at break, per cent 8.97 8. 50 Fatigue life: Cycles [lering at 250 F. to

produce failure 2, 870 13, 320 Per cent increase in fatigue life 365 Tension applied during treatment. as per cent oi breaking strength of untreated grey cord 6 Example 2.-Batch process-Figure 2 An 1800 yard length of 7.8/1 cotton yarn wound on a metal spool with a perforated barrel is immersed in a bath II consisting of an aqueous 0.14% solution ofammonia at room temperature (25 C). The Package is allowed to remain in the bath for 2 hours to permit penetration. The package is then removed from the bath and placed on a positive drive variable speed let-off spindle I2. The wet yarn is then passed through the dead load tensioning pulley I3 and rewound on a second spool on a positive drive fixed speed spindle I4. During the respooling operation just described the speed of the let-off spindle I2 is varied by manual control so as to maintain the tensioning pulley I3 at a uniform height. The Weight of the load and pulley I3 is such that av tension of about 1.9 lbs. is maintained on the yarn in transit between let-off I2 and wind-up I4. The average rate of wind-up is about yards per minute.

The respooled yarn is then `immersed in a bath I5 of amyl acetate for 4 hours at 110 C., after which it is again respooled. The second respooling operation is comparable to the rst, except that the 'load applied I'I is such that the yarn in transit between the let-off spindle I6 and the wind-up spindle I8 is maintained at a tension of 1.7 lbs.

The rewinding operation is a convenient way of applying more tension to the strand after immersion in bath I I, but other Ways may be used;

After the nal respooling the yarn is dried on the spool at '70 F. and 65% relative humidity.

This is a convenient procedure for Small packages; for larger packages the yarn may be dried by passing hot, dry air through the packages.

Yarn treated by the method of Example 2 shows a substantial increase in strength and a corresponding reduction in stretch, as illustrated by the following test data:

If desired, either or/both of the respooling operations at I4 and I8 may be eliminated, although betterV resultsfollow` such respooling.

the cord may be kept in xed' positionV and the respective solutions either sprayed or circulated thereon in succession.

Example /3/,2 cotton cord is treated as described in Example 1, QXCD th'atf Theapplied tensionivas 4.75 111s.V (equal.

Example 3 5 to 31% of the breaking strength of the untreated Y cord);.and 7.5/1 cotton yarns are treated, as described in (l)v The time of treatment .in each is Example 2, except that: varled; -at noted below, to shovv that tune of (a) Variations are made in the aqueous bath to 165 treatment m ellher @Ph .1n @XFQFQS 191131.12?? show that while water may be used for the aque- 94nd .uP t0, 2.0 mmutes 1S not Cntlcafl 111 the C011# ous bath, further improvements are gained by use tlnuous process' of an aqueous bath made slightly alkaline bythe addition of small amounts of bases, e. g., am- AUD. B C D E monia, ethylene diamine, or caustic soda; treated Treated Treated Treated Treated (b) The tension maintained is 2.0 lbs., or y Y Y about 69% of the strength of the untreated yarns. Timen'of'glfgen8% u l M L, 47M.. A .F.v` ...NAWuMU www, amm0nja v 5l 10! 10! 2O l lInAmyl acetate;' 5 5' 10l 20' Y Strength, St't'eh dstrelnbgsth' 1554 la? "14.5 19.4 pida Baths n 1.82 2. 54 2.61 2.581 -2.'57 Lbs ll/ Imrgze' Break 121.0 5.6 v 5.3 5;.4' '5.4

Per cent Per cent Y Example@ Untreated yarn..." 2.90 1.83 6.2 25` f Agma mat' 3'21 2'19 20 4'6 1073/2 cotton cord 'is treated Yas c escribed in Amyl acetate Weet- Example 1, except that the temperature of the tlrlaltnefflltymg, non-aqueous bath is 'varied as noted to show that C* tltainaa; 33 '28 "3 the tempweitere ef the nee-aqeeeee beth Sheeld E I 1%E0thy1ene'di 112 4131 29o '59vr le 39 be substantially aboveV room temperatures, and

mmegsticsoda. 11.5 4151 "3.137 s4 2.2 Dreferab1yn0t`lwer than about 50C- E-'Iampze 4 35 Untrieated Tregted Tregted Tregted 7.5/1 cotton yarn is treated as described in Example 3, except that various non-aqueous Tfrt "f amy? acetate 55 90 baths are used, Ias noted below, at 90 C., to show that a variety of commercial organic solvents may be used for the non-aqueous bath. 9.1 9. 1 7.5

Strength Stretch Baths G l I Bat k Y ms mprove rea Lbs den. ment Per cent Per cent A.. Untreated grey yarn. 2. 90 1.83 0 f 6. 2 Aqueous 0.14% Am- 3. 56 2. 46 34 2. 3

monia bath only. r Aqueous 0.14% Am- 1rionia bath followed k y C.-. yTol1'1ene 3. 94 2. 76y 51 1.9 D." Tetrachloroethylene. 4. 04 2. 86 5.6, 1 9 v Amyl acetate 4. 59 3. 13 71 2. 2 F.-. Pylidine 4. 86 l 3. 17 73 2. 5

kExamples 3 and 4 together show that the results obtainable by the combination-of the baths are more than additive. Adding the yper cent improvement of Example 3n (B)V to that Aof Example 4 (B), gives a predicted total of 54 'Z. increase in strength, Whereas in reality Example 3 (D), and Example 4 (E), show the combination treatment to give 71% improvement in strength. Note also that this increase did not require more than a tension of about A2l lbs., which is noteworthy considering that the disadvantage vof most prior art treatments of cotton strands, attempting to approach .similar strength, isA that they require tensions so vhigh as to closely approach the breaking strength Aof the-strands. For example, in British Patent No.545,716, toget' a 31% strength improvement vrequires such a high tension as to 4bring about a 75% less in stretch.

Example 7 10/3/2 cord is treated as described in Example ;=.`1, except for the variations in tension as'noted below, to show that in the continuous method the strength is improved as the tension applied is in` creased up to a value equal to around 20% of the strength of the untreated material; at higher tensions the stretch is V'further reduced without any apparent further increase in strength.

'7.1/1 cottonyarn is'treated as described Example 2, except that the tension applied is varied as noted below to show that'the strength of the yarns treated according to the batch method improves as the tension applied 'is increased up to about of the breaking strength ofthe untreated yarn. At this point it appears that higher lapplied tension Would result in a substantial re- Auctionv in `stretch Without a compensating iiicrease in strength.

/3/2 cotton cords are treated as described in Example 1, except that:

(a) A tension of 4.2 lbs. is applied, equivalent to 27% of the breaking strength of the untreated cord; and

(b) The various cords are treated by a single bath or by both baths as indicated.

This example shows further that the improvement gained by the use of the aqueous and nonaqueous baths in succession is substantially greater than the improvement gained by treatment with either bath alone. The eiect of the invention as disclosed is likewise greater than and cordsr treated by the continuous procedure (as in Example 1). l

Treated ByrrUld c ea e ontw Process 1013/2 COTTON CORD Tension applied:

lha 4. 5 10. 0 as per cent of untreated strength-. 66 S ength:

7.1/1 COTTON YARN Tension applied:

im 1.0 2.0 as per cent of untreated strength 38 77 Strength:

Example 12 This example shows the strength, and strength improvement, of yarns treated by my invention would be predicted from the separate effects of `30 and tested both bone dry and at 65% humidity.

the aqueous and non-aqueous treatments.

The data show that the treated yarn is less af- A Untreated B Treated D Treated Aqueous bath Non-aqueous bath Strength:

lbs

gms/den Stretch at break, per cent Per cent increase in grey strength.

0.28% Ammonia.--

0.28% Ammonia. Amy] acetate.

Example 10 18 /4/3 cotton cord is treated as described in Example 1, except that the tension applied is 2.2 lbs., corresponding to 12% of the breaking strength of the untreated cord, to show that the order in which the cord is treated in the two baths is immaterial.

A Untreated B Treated C Treated lst Treat-ineut 2nd Treatment. Tension used.-.

0.28% Ammonia.--

Amyl acetate. 0.28% Ammonia. 2.2 lbs.

Strength:

lbs 23.2. gms/den.. 2.86. Stretch at breaky per cent-... 9.8 6.3 6.4.

Example 1 1 This example shows that by suitable adjustment of the applied tension, yarns and cords treated by the batch procedure (as in Example 2) may be made equal in quality to comparable yarns iected than the untreated yarn by lowering the moisture content. Y

7.8/1 yarn is treated exactly as described in Example 2.

This example shows the relative effects of processing, according to this invention, cotton yarn composed of grey bers (containing the native cotton waxes), and cotton yarn from which the non-cellulosic constituents have rst been extracted with ethanol. Note that even in the case of the extracted cotton there is an increase in tensile strength, but materially less than when grey cotton is treated.

[7.8/1 cotton yarns] Extracted Not extracted with ethanol,

72 hrs.

A B C D Per cent Extractable Material in Yarn before treatment 1. 75 1. 75 0. 25 0.25 Treatment Nono (l) None (l) Per cent Extractable Material in yarn after treatment 1. 75 0. 90 0.25 0.10 Strength:

in lbs 2. 80 4. 82 3. 44 4. 40 in gms/den 1. 84 3.31 2. 37 3.09 Per cent Increase en 80 29 68 Stretch at break, per cent 5.4 2. 7 5. 4 2. 3

1 As in EX. 2.

Example 14 This example further illustrates that the efects obtained are more than the sum of the effects from treating with water alone and from treating with the organic solvent alone. In this example 10/3/2 cotton cords are treated, respectively, with water alone, with amyl acetate alone, and with amyl acetate followed by water the tension applied during the bath treatments is about 27% of the breaking strength of the untreated cord.

Strength Per Cent Per Cent Tension Stretch Increase (lbs.) (at in lbs. g./d. Break) Strength Untreated unwetted ,f grey cord 15.7 1.87 14.0 Arnyl acetate alone 4.2 17.4 2.13 10.8 14 Water alone 4.2 16.6 2.17 5.7 16 Amyl acetate and then Water 4,2 19.0 2.58 4.8 38

Example 12.4/1 cotton yarns are treatedas described in Example 2, except that:

(o.) Variations are made in the aqueous swelling bath to show that, while dilute aqueous ammonia may be used, further improvements in strength and stretch may be gained by use of a more concentrated aqueous solution of ammonia;

(b) The tension applied is 1.0 lb., or about 67% of the breaking strength of the untreated It Will be apparent that by this invention it is possible to treat cotton yarns .and cords inexto provide cotton textile materials with greatly increased strength, and without the use of excessively high tension or prolonged washing.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A method of improving the tensile strength of stranded grey cotton bers which comprises subjecting them to successive contact with two liquids, one being a dilute aqueous ammonia solution, and the other being an organic liquid having the property of dissolving cotton waxes comprising an alkyl acetate the alkyl group having from 3 to 5 carbon atoms, the solvent treatment being carried out at a temperature substantially above 25 C., but not in excess of 150 C., the entire liquid treatment allowing maintenance in the fibers of a substantial proportion of the original cotton waxes, and drying the fibers, and maintaining the stranded bers under a marked tension materially7 less than the breaking strength of the untreated stranded fibers during at least part of the liquid treatment.

2. A method of improving the tensile strength of stranded grey cotton iibers Which comprises subjectingv them to successive contact with tWo liquids, one being a dilute aqueous ammonia solution, and the other being an organic liquid having the property of dissolving cotton waxes comprising amyl acetate, the solvent treatment being carried out at a temperature substantially above 25 C., but not in excess of 150 C., the entire liquid treatment allowing maintenance in the fibers of a substantial proportion of the original cotton waxes, and drying the fibers, and maintaining the stranded fibers under a marked tension materially less than the breaking strength of the untreated stranded bers during at least part of the liquid pensively, by a simple two-step chemical process treatment.

HENDRIK ROMEYN, J a.

REFERENCES CITED The -following references are of record in the file of this patent:

y UNITED STATES PATENTS Number Name Date 909,457 Rousseau Jan. 12, 1909 1,398,378 Jacoby Nov. 29, 1921 1,596,100 Hiltner Aug. 17, 1926 1,962,424 Brownell Feb. 8, 1930 2,126,809 Pratt Aug. 16, 1938 2,137,339 Gwaltney Nov. 22, 1938 2,156,923 Picard May 2, 1939 2,173,997 Burgeni Sept. 26, 1939 2,297,536 Buckwalter Sept. 29, 1942 2,346,126 Lessig Apr. 11, 1944 2,364,467 Nickerson Dec. 5, 1944 2,372,561 Elgin Mar. 27, 1945 2,398,787 Hansen Apr. 23, 194

FOREIGN PATENTS f.

Number Country Date 545,716 Great Britain June 9, 1942 OTHER 'REFERENCES Leger et al.: Pectin Substances in Cotton, Canadian J. RGS. 1941, 19B, 61-64. 

1. A METHOD OF IMPROVING THE TENSILE STRENGTH OF STRANDED GREY COTTON FIBERS WHICH COMPRISES SUBJECTING THEM TO SUCCESSIVE CONTACT WITH TWO LIQUIDS, ONE BEING A DILUTE AQUEOUS AMMONIA SOLUTION, AND THE OTHER BEING AN ORGANIC LIQUID HAVING THE PROPERTY OF DISSOLVING COTTOM WAXES COMPRISING AN ALKYL ACETATE THE ALKYL GROUP HAVINGFROM 3 TO 5 CARBON ATOMS, THE SOLVENT TREATMENT BEING CARRIED OUT AT A TEMPERATURE SUBSTANTIALLY ABOVE 25* C., BUT NOT IN EXCESS OF 150* C., THE ENTIRE LIQUID TREATMENT ALLOWING MAINTENANCE IN THE FIBERS OF A SUBSTANTIAL PROPORTION OF THE ORIGINAL COTTON WAXES, AND DRYING THE FIBERS, AND MAINTAINING THE STRANDED FIBERS UNDER A MARKED TENSION MATERIALLY LESS THAN THE BREAKING STRENGTH OF THE UNTREATED STRANDED FIBERS DURING AT LEAST PART OF THE LIQUID TREATMENT. 